Ed,

What you are referring to is actually the “extractor”, and Yes, it appears to be thicker (heavier) than standard.  The .22 rim fire Single Shots were factory fitted with an “ejector” spring to aid the extractor in kicking the empty clear of the chamber and breech.  The attached picture shows the wire spring and the screw that retains it in the action.

Bert

Edward Kitner said
I thought it appeared heavier, wonder why?

It is a nice set up though.  I just lay the round on the extractor with the bullet end in the chamber, then close it.  You do not have to worry about the rim getting behind the extractor.

  

I suspect that the original extractor broke (a very common occurrence on the .22 rim fires) and when it was replaced, the owner was thinking ahead and modified the barrel breech for a thicker (stronger) extractor.  Can you measure what the thickness is?  When I get back home later this week, I will measure a couple of mine to see what the difference is.

Bert

Edward Kitner said
I could just barely get my calipers in.  The extractor appears to be tapered from .115″on the left to .085 on the right.

  

Ed,

I just inspected two of my Single Shot rifles (a 2 Short and a 22 Long R) and both have what appears to be the same size/dimension extractor as your rifle.

Bert